Embedded processors in end-user devices are commonly known. Within this context, an embedded processor is a special-purpose microprocessor embedded in the device it controls. In contrast to a general-purpose processor, such as those for use in a personal computer (PC), an embedded processor performs a limited number of pre-defined tasks, typically with very specific requirements and a specific instruction set. Since the processor is dedicated to specific tasks, design engineers can optimize it, reducing its size and cost. An end-user device within this context is an electronic device whose main functionality is intended for everyday use by the end-user, typically a consumer. Examples of user devices are a mobile telephone, another personal communication device, a navigational aid, an ADSL modem, etc.
Typical examples of such processors are the DSTni-LX/DSTni-EX embedded processors from Lantronix, the NS7520 Microprocessor from Netsilicon, the ADSP-21xx Processor and Blackfin Processors from Analog Devices.
Other examples are the processors with an x86-compatible CPU of the 80286 series. These processors have an operational mode referred to as the “protected mode” that serves to limit access by a software program to certain processor instructions and addressable memory areas, to the discretion of the developer of that program. That is, the conditions for limited access are set during programming. For more background see, e.g., “Overview of the Protected Mode Operation of the Intel Architecture”, author Steve Gorman, a white paper published by Intel Corporation.